Al Hishah Gr

Period:

Neogene

Age Interval:

Zanclean

Province:
Cyrenaica Basin

Type Locality and Naming

According to Shaltami et al. (2020), this group consists of a lower Umm Al Gharaniq Fm separated by a major hiatus (ca. 30% of the Zanclean) from the overlying Uyun Ghuzayil Fm. [Neither of those formations were indicated on stratigraphic charts in other publications consulted during preparation of this lexicon.]

Synonym: Al Hishah Fm

References: Shaltami, O.R., et al. (2020), and Google Gemina (Aug’26)

Lithology and Thickness

Primarily composed of fossiliferous calcarenites, sandy limestones, marls, gypsiferous clays, and cross-bedded shoreline sandstones.

Lithology Pattern:

Clayey limestone

Relationships and Distribution

Lower contact

Unconformable onto the Al Abyar Fm of the Ar Rajmah Gr according to Shaltami et al. (2020). “It overlies the late Miocene (Messinian) evaporites or shallow-marine limestones of the Ar-Rajmah Group following the regional Messinian Salinity Crisis draw-down.”

Upper contact

Unconformably overlain by the Quaternary coastal calcarenites of the Qarat Al Asi Fm of the Qarat Weddah Gr according to Shaltami et al. (2020).

Regional extent

Mapped across the coastal margins of the Cyrenaica Basin and extending west toward the Sirt Basin in northern Libya. Forms distinctive shoreline ridge-and-runnel landforms and lithified fossil dune ridges running parallel to the modern Mediterranean coast. (Google Gemini overview)

GeoJSON

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Fossils

Age

Zanclean according to Shaltami et al. (2020). [For graphic purposes, the extent of the upper and lower unconformities, which are equivalent to nearly the same time span of the known preserved deposits, have been omitted here.]

Age Span:

Beginning stage:

Zanclean

Fraction up in beginning stage:

0.0

Beginning date (Ma):

5.34

Ending stage:

Zanclean

Fraction up in the ending stage:

1.0

Ending date (Ma):

3.60

Depositional setting

Represents a shallow-marine to estuarine and lagoonal/sabkha transition. During the Early Pliocene, post-Messinian sea-level rise inundated the North African margin, creating shallow coastal embayments and barrier-island systems.

Depositional pattern:

Additional Information

Compiler:

Shaltami, O.R., et al. (2020). Petroleum system of the Cyrenaica Basin – A review. In: 1^st International Symposium on Geosciences (ISG2020), 21th March 2020, Proceeding Book: published by BR Petrobras. P. 64-71.

Tawadros, E.E. (2011). Geology of North Africa. CRC Press (Taylor & Francis Group), 931 pp.

Google Gemini (Aug 2026) – assembled synthesis of Cyrenaica Basin units from various web-accessible publications.

El Oshebi, F.M., Fares, F.F. (2026). Stratigraphy, facies, and depositional environments of the Eocene sequence in the Ras Al Hilal area, Cyrenaica, Libya. Arabian Jour. Geosciences, 19:79. https://doi.org/10.1007/s12517-026-12488-2.

El-Hawat, A.S., Abdulsamad, E.O. (2004) Geology and Archeology of Cyrenaica, Northeastern Libya. Field trip guide B01, 32^nd International Geological Congress. 36 pp.